JP5633006B2 - Friction stir processing apparatus and friction stir processing method - Google Patents

Description

  The present invention relates to, for example, a friction stir processing apparatus and a friction stir processing method in which a tool that rotates along a joining line where metal workpieces are abutted against each other is pressed and softened by friction heat to join.

  Friction stir welding (FSW) is known as the processing method. Friction stir welding softens the work material by the frictional heat generated by rotating the cylindrical tool against the joining line where the work materials made of metal materials face each other and rotating it in the joining direction. It is the method of making it join. In addition, using the above tools, friction stir modification (FSP) for improving the strength and hardness of the workpiece surface, and friction stir spot welding (FSJ) for spot welding the workpiece are also performed. The friction stir welding is generally referred to as friction stir processing.

  The tool includes a cylindrical tool body, a circular shoulder surface that contacts the workpiece in the tool body, and a probe that protrudes from the center of the shoulder surface and is pushed into the workpiece (FIG. 3). . The tool is required to have a material having higher physical properties such as hardness, melting point, and wear resistance than the workpiece, and tool steel such as SKD steel is mainly used for joining the workpiece such as aluminum. ing. On the other hand, tools such as ceramics or cemented carbide are used for joining workpieces made of iron-based materials such as stainless steel, which has a higher melting point than aluminum materials. However, ceramic tools are easily damaged, and cemented carbide tools are prone to wear in a short time. Therefore, a material made of a Ni-based double-duplex intermetallic compound alloy having high strength and excellent high-temperature characteristics has been proposed as a tool material (Patent Document 2).

  In addition, when the tool depth (the amount of pushing of the shoulder surface from the workpiece surface) into the workpiece during the friction stir processing is fluctuated, defects are likely to occur at the joint. Therefore, to prevent such defects, the vertical position of the tool is constantly adjusted so that the tool load detected during machining is constant based on the correlation between the tool load received by the tool from the workpiece and the tool depth. A load control technique for keeping the tool depth constant by adjusting is known (Patent Document 1).

JP 2001-198683 A JP 2009-255170 A

  By the way, the tool is worn and shortened by a machining operation depending on the combination of the tool and the workpiece, for example, when a ferrous material is joined with a tool made of cemented carbide or the like. For this reason, when the workpiece is sequentially processed a plurality of times, a sufficient contact area cannot be secured between the tool and the workpiece, and a defect is generated in the processed portion. In addition, the wear of the tool is significant on the shoulder surface, and the probe is not so worn. This is because the contact speed with the workpiece is fast on the shoulder surface and slow on the probe at the center position of the shoulder surface, so the wear speed is higher on the shoulder surface. Therefore, when the wear of the tool progresses, the probe length tends to be apparently long in relation to the shoulder surface. In this case, according to the load control, the contact area between the shoulder surface and the workpiece is kept constant, so that the apparently long probe insertion depth into the workpiece is increased. And if the insertion depth of a probe with little wear exceeds the plate | board thickness of a workpiece due to the tool depth fluctuation | variation by load fluctuation | variation, defects, such as a burr | flash and a cavity, will be produced in a process part. Such a phenomenon is remarkable when the workpiece is a thin plate (for example, a plate thickness of 1.5 mm or less). In the case of a thin plate, it is easy to be affected by the fluctuation of the tool pressing load by the processing device, and since the fluctuation range of the tool pressing load allowed during processing is small for the thin plate, the above load control should be appropriately executed. Because it is difficult.

  In view of the above circumstances, the present invention provides a friction stir processing apparatus and a friction stir processing method that can cope with tool wear due to repeated processing operations and that can perform good processing by suppressing the occurrence of defects. .

The friction stir processing apparatus according to the present invention is:
A tool for projecting a probe on the shoulder surface and friction stir processing a workpiece made of a metal material;
Rotational drive means for rotating the tool;
Elevating drive means for setting the tool height to move the tool up and down and press against the workpiece from above,
Transfer drive means for moving the tool relative to the processing direction of the workpiece;
The above tool height when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the first material to be processed as the reference tool height, and the second and subsequent times. In order to secure the necessary contact area between the shoulder surface of the tool and the workpiece, in response to the decrease in the shoulder height due to tool wear due to machining operations Tool height adjusting means for controlling the lifting drive means so as to be set lower than the reference tool height by a predetermined lowering width.

  The tool height adjustment means adjusts the tool height according to the wear of the tool for workpieces to be processed after the second time. A large contact area can be ensured. Moreover, even if the workpiece is difficult to adjust in height by conventional load control because the allowable fluctuation range of the tool load is relatively small like a thin plate, the tool height control means described above Since the tool height is adjusted in accordance with the wear of the tool, a sufficient contact area can be ensured between the shoulder surface of the tool and the workpiece. Therefore, even if the machining operation on the workpiece is repeated using the same tool, the amount of frictional heat generated by the tool can be appropriately controlled without excess and deficiency, and the occurrence of defects in the machined portion is suppressed.

  The tool is preferably made of a Ni-based double-duplex intermetallic compound alloy, and the workpiece is preferably made of a plate material of an iron-based material.

  Thereby, the heat resistance and wear resistance of the tool are improved, and the tool can exhibit the necessary hardness even under high temperature due to frictional heat during processing. Therefore, even if a machining operation is repeated using the same tool on a workpiece made of an iron-based material such as stainless steel that has a relatively high temperature during machining, a good machining state can be realized.

In the friction stir processing apparatus,
It is preferable to provide a tool regeneration mechanism for grinding the tool worn by friction stir processing with a grindstone.

  When the tool is worn, the contact state between the tool and the workpiece becomes unstable, and a good bonded state cannot be obtained. On the other hand, according to the tool regeneration mechanism, even if the tool is worn, the tool regeneration mechanism can grind and regenerate the tool. Therefore, since the worn tool can be reused by regeneration, the tool life can be extended, the frequency of tool replacement can be reduced, and the processing cost of the workpiece can be reduced.

  By the way, tool wear due to repeated machining operations is marked on the shoulder surface, and the probe is not so worn. Therefore, if the tool push-in amount is increased by the amount of decrease in the tool load due to wear on the shoulder surface as in conventional load control, the probe insertion depth exceeds the plate thickness of the workpiece, and the processed part This causes defects such as burrs and cavities.

Therefore, the tool regeneration mechanism can be configured to grind only the probe of the tool with a grindstone.
As a result, the probe length, which has become longer due to significant wear on the shoulder surface of the tool due to repeated machining operations, is ground by the above-mentioned tool regeneration mechanism, so that the probe length corresponds to the thickness of the workpiece. Can be played back to length. Therefore, since the tool wear can be dealt with by regenerating the tool, even if the machining operation to the workpiece is repeated using the same tool, the occurrence of defects in the machined portion is suppressed, which is good. The machining state can be realized. Further, if only the probe is reproduced, the tool can be reproduced easily and quickly.

The friction stir processing apparatus according to the present invention is
A tool for projecting a probe on the shoulder surface and friction stir processing a workpiece made of a metal material;
Rotational drive means for rotating the tool;
Elevating drive means for setting the tool height to move the tool up and down and press against the workpiece from above,
Transfer drive means for moving the tool relative to the processing direction of the workpiece;
The above tool height when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the first material to be processed as the reference tool height, and the second and subsequent times. For workpieces to be machined, only a predetermined reduction width is required to ensure the necessary contact area between the shoulder surface of the tool and the workpiece in response to tool wear due to machining operations. Tool height adjusting means for controlling the elevating drive means to be set lower than the reference tool height;
A tool regeneration mechanism for grinding the tool worn by friction stir processing with a grindstone;
At the time of reproduction by the tool reproduction mechanism, the tool is rotated so as to grind the tool while rotating the tool, and the output value of the torque detection means for detecting the rotation torque of the tool or the rotation torque of the grindstone is a predetermined value. it reaches the set value and Ru and a reproduction control means for controlling to stop playing.

  As a result, the rotational torque of the tool or the grindstone is detected by the torque detection means when the tool is reproduced, and for example, the rotational torque value when the surface shape of the tool is in an appropriate state is set as the set value. By stopping the reproduction when the value is reached, it is possible to perform a good tool reproduction without wasting time and not cutting too much.

In addition, the friction stir processing method according to the present invention,
A friction stir processing method for softening and processing a workpiece by friction heat generated by pressing a tool against a workpiece of metal material while rotating the tool,
The tool height for pressing the workpiece from the top when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the workpiece to be processed first. For the workpiece to be processed at the second and subsequent times, the required contact between the shoulder surface of the tool and the workpiece corresponding to the amount of reduction in the shoulder height due to wear of the tool by the machining operation In order to ensure the area, the workpiece is processed while being set lower than the reference tool height by a predetermined reduction width.

  As a result, a sufficient contact area can be ensured between the shoulder surface of the tool and the workpiece corresponding to the wear of the tool due to the machining operation on the workpiece. Therefore, even if the machining operation on the workpiece is repeated using the same tool, the amount of frictional heat generated by the tool can be appropriately controlled without excess and deficiency, and the occurrence of defects in the machined portion is suppressed. As a case where it is difficult to sufficiently prevent defects with the conventional load control, for example, the frictional heat generated by the tool is also applied to a workpiece having a relatively small allowable fluctuation range of the tool load, such as a thin plate. The amount of generated heat can be appropriately controlled without excess or deficiency, and the occurrence of defects in the processed portion can be suppressed.

  As described above, according to the friction stir processing apparatus and the friction stir processing method according to the present invention, even if the processing operation on the workpiece is repeated using the same tool, it is possible to cope with tool wear and processing. It is possible to suppress the generation of defects in the part and realize a good processing state. Moreover, even if the workpiece is a thin plate, a good machining state can be realized.

It is a perspective view which shows the whole structure of a friction stir welding apparatus. It is a schematic diagram for demonstrating the mechanism which sets the tool height in a friction stir welding apparatus. It is a figure which shows the tool for friction stirring processing, the figure (A) is a perspective view of a tool, and the figure (B) is the side view. It is sectional drawing to which the part of the tool grinding apparatus as a tool reproduction | regeneration mechanism of a friction stir welding apparatus was expanded. It is a schematic diagram which shows the relationship between a workpiece processing operation position and a tool reproduction | regeneration operation position. It is a graph which shows the correlation of the processing distance in Example 1, and tool wear. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (1st time) of the friction stir welding of Example 1 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (7th time) of the friction stir welding of Example 1 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by the processing operation (13th time) of the friction stir welding of Example 1 from the front side. It is a graph which shows the correlation of the processing distance in Example 2, and tool wear. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (1st time) of the friction stir welding of Example 2 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (seventh) of the friction stir welding of Example 2 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (14th time) of the friction stir welding of Example 2 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (before reproduction | regeneration) of the friction stir welding of Example 3 from the front side. It is the photograph which image | photographed the junction part of the thin plate obtained by processing operation (after reproduction | regeneration) of the friction stir welding of Example 3 from the front side.

  Hereinafter, as an embodiment of a friction stir processing apparatus, a friction stir welding apparatus for performing friction stir welding on a plate material (hereinafter referred to as “workpiece” as appropriate) as a workpiece of a metal material will be described as an example. As shown in FIG. 1, the friction stir welding apparatus 1 includes a processing mechanism 2 for performing friction stir welding on workpieces W <b> 1 and W <b> 2 on a base 7.

On the base 7, a jig 4 for arranging two flat workpieces W1, W2 is provided, and a backing material 41 arranged on the back surface of the works W1, W2 is attached to the jig 4. . The workpieces W1 and W2 are fixed by a workpiece presser 6 provided on the jig 4 so that a joining line L that abuts each other's end faces is positioned at the center of the backing material 41. The material of the backing material 41 is preferably made of ceramics, but is not limited thereto. For example, if the workpieces W1 and W2 are iron-based alloy plate materials, a material having a low thermal conductivity (for example, Si ₃ N ₄ ) that can block heat radiation from the back side of the plate materials is selected in order to achieve good bonding. It is possible. In addition, you may comprise the backing material 41 by a rod-shaped member etc. other than the flat plate member as shown in FIG.

  The processing mechanism 2 raises and lowers the tool 20 for friction stir processing, a tool holding unit 30 for holding the tool 20, a rotation motor (rotation drive means) 32 for rotating the tool 20, and the tool holding unit 30. And an elevating motor (elevating drive means) 85 and a transfer motor (transfer driving means) 83 for moving the tool holding unit 30 in the lateral direction.

  The tool holding unit 30 includes a tool holder 3 to which the tool 20 is detachably attached. The tool holder 3 is connected to a tool rotation motor 23, and the tool 20 is rotated together with the tool holder 3 by driving the tool rotation motor 23. As shown in FIG. 2, the tool holding unit 30 is attached to the slider 80 by a ball screw 86 so as to be movable up and down, and is movable up and down with respect to the base 7 by a lifting motor 85 provided on the slider 80. Thereby, the tool height which makes the tool 20 contact workpiece | work W1, W2 is set. The tool holding unit 30 is rotatably attached to the slider 80 so that the tool 20 can be set to a predetermined advance angle θ (see FIG. 5). The slider 80 is attached to a linear motion mechanism 84 having a pair of guide rails 81 and a ball screw 82, and is moved in parallel with the base 7 by driving of a feed motor 83. Thereby, since the tool holding part 30 attached to the slider 80 is moved, the tool 20 hold | maintained at the tool holding part 30 is moved along the joining line L direction used as the process direction of workpiece | work W1, W2.

(Friction stir processing tool)
As shown in FIG. 3, the tool 20 includes a columnar tool main body 21 and a hexagonal columnar mounting portion 24 formed on the base end side of the tool main body 21 via a flange 25. The tool 20 is attached to the tool holding part 30 by the attachment part 24 being detachably fixed to the tool holder 3. The distal end surface of the tool main body 21 has a planar shoulder surface 22 and a spherical probe 23 protruding from the center of the shoulder surface 22. When the workpieces 20 are subjected to friction stir processing, the tool 20 presses the shoulder surface 22 and the probe 23 of the tool main body 21 against the workpieces W1 and W2 while rotating to generate frictional heat.

  Tool 20 is preferably formed from a Ni-based two-duplex intermetallic alloy. As a result, the heat resistance and wear resistance of the tool 20 are improved, the tool 20 can exhibit the necessary hardness even under high temperatures due to frictional heat during processing, and the workpiece has a higher melting point than aluminum alloy or the like. Even if it is a ferrous alloy etc. which are materials, reliable and favorable joining can be performed.

For example, Ni ₃ Al (L1 ₂ ) —Ni ₃ Ti (D 0 ₂₄ ) —Ni ₃ V (D 0 ₂₂ ) intermetallic compound alloy (International Publication WO2006 / 1011212 pamphlet) And Ni ₃ Al (L1 ₂ ) —Ni ₃ Nb (D 0 _a ) —Ni ₃ V (D 0 ₂₂ ) intermetallic compound alloy (see International Publication WO2007 / 086185 pamphlet) and the like are known.

As the _{Ni 3 Al (L1 2) -Ni} 3 Ti (D0 24) -Ni 3 V (D0 22) based phase intermetallic alloy, specifically, Al: at greater than 5 atomic% 13 atomic% or less, V: 9.5 atomic% or more and smaller than 17.5 atomic%, Ti: 0 atomic% or more and 3.5 atomic% or less, B: 0 weight ppm or more and 1000 weight ppm or less, and the balance is from Ni except impurities. And a Ni ₃ Al-based intermetallic compound having a double-phase structure of a proeutectoid L1 ₂ phase and a (L1 ₂ + D0 ₂₂ ) eutectoid structure.

This intermetallic compound is Al: greater than 5 atomic% and 13 atomic% or less, V: 9.5 atomic% or more and less than 17.5 atomic%, Ti: 0 atomic% or more and 3.5 atomic% or less, B: 0 ppm by weight or more in 1000 ppm by weight or less, the balance being the alloy material consisting of Ni remove impurities, performing a first heat treatment at a temperature at which coexist with proeutectoid L1 ₂ phase and Al phase, then L1 ₂ phase If either is the D0 ₂₂ phase is cooled to a temperature to coexist, the change by performing the second heat treatment at a temperature and the L1 ₂ phase and D0 ₂₂ phase coexist, the Al phase (L1 ₂ + D0 ₂₂₎ eutectoid tissue And can be produced by a method comprising a step of forming a double-duplex structure. Alternatively, it can also be produced by a method comprising a step of forming a double-duplex structure by slowly cooling an alloy having the above composition from a high-temperature A1 single phase region.

Further, the _Ni 3 _{Al (L1} 2) as _{-Ni 3 Nb (D0 a) -Ni} 3 V (D0 22) based intermetallic compound alloy, specifically, Al: Large 13 atomic% or less than 5 atomic% V: 9.5 atomic% or more and less than 17.5 atomic%, Nb: 0 atomic% or more and 5 atomic% or less, B: 50 weight ppm or more and 1000 weight ppm or less, the balance is made of Ni except impurities, Examples thereof include a Ni ₃ Al group intermetallic compound having a double overlapping phase structure of a proeutectoid L1 ₂ phase and a (L1 ₂ + D0 ₂₂ ) eutectoid structure.

This intermetallic compound has Al: greater than 5 atomic% and 13 atomic% or less, V: 9.5 atomic% or more and less than 17.5 atomic%, Nb: 0 atomic% or more and 5 atomic% or less, B: 1000 ppm by weight to 50 ppm by weight or less, the balance being the alloy material consisting of Ni remove impurities, proeutectoid L1 ₂ phase and Al phase and the temperature to coexist, or the pro-eutectoid L1 ₂ phase and Al phase and D0 _a The first heat treatment is performed at a temperature at which the Al phase coexists, and then the Al phase is cooled to a temperature at which the L1 ₂ phase and the D0 ₂₂ phase coexist, or the second heat treatment is performed at that temperature, whereby the Al phase is (L1 ₂ + D0 ₂₂ ). It can be manufactured by a process of changing to a eutectoid structure to form a double-duplex structure. Alternatively, it can also be produced by a method comprising a step of forming a double-duplex structure by slowly cooling an alloy having the above composition from a high-temperature A1 single phase region.

The material of the tool 20 is mainly composed of Ni and Al: 2 to 9 atomic%, V: 10 to 17 atomic%, Ta and / or W: 0.5 to 8 atomic%, Nb: 0 to 6 B: 10 to 1000 ppm by weight and the proeutectoid L1 ₂ phase (L1) with respect to the total weight of the composition of a total of 100 atomic% including atomic%, Co: 0 to 6 atomic%, Cr: 0 to 6 atomic% ₂ + D0 ₂₂ ) A Ni-based double-duplex intermetallic compound alloy having a double-duplex structure composed of a eutectoid structure is preferable in terms of excellent heat resistance and wear resistance. In the present specification, the above “to” includes an upper limit value and a lower limit value, respectively.
When Ta and / or W is contained in an amount of 0.5 to 8 atomic%, an effect of improving hardness can be obtained.
Nb, Co, and Cr are optional components, but Nb is added to improve the strength of the double-phase structure, and Co and Cr are added to improve oxidation resistance.
B is added to improve the ductility of the obtained alloy.
In addition, the intermetallic compound alloy is excellent in mechanical properties such as tensile strength and creep resistance by having a double-duplex structure composed of a proeutectoid L1 ₂ phase and a (L1 ₂ + D0 ₂₂ ) eutectoid structure. .

The material of the tool 20 is mainly composed of Ni and Al: 5.5 to 13 atomic%, V: 10 to 17 atomic%, Nb: 0 to 6 atomic%, Ti: 0 to 6 atomic%, Co : B: 10 to 1000 ppm by weight with respect to the total weight of the composition of a total of 100 atom% including 0 to 6 atom%, Cr: 0 to 6 atom%, and the proeutectoid L1 ₂ phase (L1 ₂ + D0 ₂₂ ) A Ni-based double-duplex intermetallic compound alloy having a double-duplex structure composed of a eutectoid structure is also preferable from the viewpoint of excellent heat resistance and wear resistance, as described above.

  The tool 20 may be manufactured by a melting / casting method, a plastic material such as hot forging, or a powder metallurgy method. For example, the manufacture of the Ni-based two-duplex intermetallic alloy tool 20 can be performed by various manufacturing methods, and a predetermined element metal (having a purity of 99.9% by weight) so as to have a predetermined composition. An ingot is prepared by melting and casting the above-described (weighed) and B by vacuum induction melting method, arc melting method or the like. A tool can be manufactured by processing this ingot into a predetermined shape by appropriately using electric discharge machining, cutting, grinding, polishing, or the like.

  When the workpieces W1 and W2 are joined by the friction stir welding apparatus 1, the tool 20 rotated at a high speed (for example, about 500 rpm to 2000 rpm) is pressed against one end of the joining line L of the workpieces W1 and W2. Then, the works W1 and W2 around the joining line L are softened by the generated frictional heat. Next, by moving the tool 20 toward the other end of the joining line L, the works W1 and W2 around the joining line L are continuously softened by frictional heat due to rotation, and the vicinity of the joining line L between the works W1 and W2 Joined by friction stir.

(Tool height adjustment means)
Further, the friction stir welding apparatus 1 repeatedly performs a machining operation corresponding to the wear of the tool 20 when the same material 20 (workpieces W1, W2) is sequentially subjected to friction stir processing a plurality of times. Each time, a tool height adjusting means 88 for controlling the elevating motor 85 so as to set the tool height low is provided (see FIG. 1).

  That is, the tool 20 is worn and shortened by repeating the machining operation of the workpiece. The degree of wear of the tool varies depending on the material of the workpiece, the material of the tool 20, the number of rotations of the tool, the machining speed, and the like. 6, see FIG. Therefore, with respect to the degree of tool wear, correlation data of tool wear with respect to the machining distance under the same conditions is obtained from the experimental results when the same material is subjected to friction stir welding with the same tool 20 at a constant tool rotation speed. To do.

  Then, in the tool height adjusting means 88, based on the tool wear correlation data, between the shoulder surface 22 of the tool 20 and the workpiece for the workpiece to be processed for the second time or later under the same conditions. The tool height at which the necessary contact area is ensured is determined, and a lowering width that is lower than the tool height (reference tool height) set for the workpiece to be processed first is set in advance. The necessary contact area between the shoulder surface of the tool 20 and the workpiece is, for example, preferably 70% or more of the shoulder surface.

  Next, the tool height when the workpieces of the same material are sequentially friction stir welded a plurality of times by the same tool 20 is the same as the workpiece to be machined the second time and thereafter by the tool height adjusting means 88. Accordingly, the lifting motor 85 is controlled so that the lowering width is set lower than the reference tool height in accordance with the wear of the tool 20 due to the machining operation. The tool height (reference tool height) set for the workpiece to be processed first is set to a tool height at which 70% or more of the shoulder surface 22 is in contact with the workpiece. Preferably, the reference tool height is pressed into the shoulder surface 22 work material by a predetermined depth from the position where the shoulder surface 22 contacts the surface of the work material, taking into account the advance angle θ of the tool 20, for example. It is the position when.

  Since the tool height is adjusted by the tool height adjusting means 88 in accordance with the wear of the tool 20, the shoulder surface 22 of the tool 20 and the workpiece can be processed even for the workpiece to be processed after the second time. A sufficient contact area can be ensured. Therefore, even if the machining operation on the workpiece is repeated using the same tool 20, the amount of frictional heat generated by the tool 20 can be appropriately controlled without excess or deficiency, and the occurrence of defects at the joint is suppressed. The

  As a case where it is difficult to sufficiently prevent defects with conventional load control, for example, a workpiece having a relatively small allowable variation range of the tool load such as a thin plate (for example, a plate thickness of 1.5 mm or less). However, the amount of heat generated by the frictional heat generated by the tool 20 can be appropriately controlled without excess or deficiency, and the occurrence of defects at the joint can be suppressed.

  Therefore, even if the machining operation on the workpiece is repeated using the same tool 20, it is possible to cope with the wear of the tool 20, and to suppress the occurrence of defects at the joint and realize a good joined state. Can do. In addition, even when the workpiece is a thin plate, a good bonding state can be realized.

  When the tool 20 is reproduced by the following tool reproduction mechanism, the tool height adjusting means 88 sets the reference tool height again for the first workpiece to be processed after reproduction, and reproduces the tool height adjustment means 88. For the workpiece to be machined after the second time, the raising / lowering motor 85 is controlled so as to be set lower than the reference tool height newly set after reproduction by the lowering width.

(Tool playback mechanism)
In addition, the friction stir welding apparatus 1 includes a tool grinding device 5 as a tool regeneration mechanism that regenerates the tool 20 worn by friction stir processing on one side of the base 7 adjacent to the jig 4. .

  By the way, the tool 20 wears when the machining operation is repeated, but the wear of the tool 20 is notably worn on the shoulder surface 22, and the probe 23 is not worn so much. This is because the contact speed with the workpiece is fast on the shoulder surface 22 and slow on the probe 23 at the center position of the shoulder surface 22. Therefore, the probe length tends to increase as the wear of the tool 20 progresses. In this case, since the contact area between the shoulder surface and the workpiece is kept constant in the above-described joining by load control, the insertion depth of the probe 23 with less wear when the load fluctuates causes the plate thickness of the workpiece to be reduced. Beyond that, defects such as burrs and cavities are likely to occur in the joint portion of the workpiece.

  Therefore, the tool grinding device 5 grinds the probe 23 that has become apparently long due to significant wear of the shoulder surface 22 of the tool 20. As shown in FIG. 3, the tool grinding apparatus 5 is connected to a grindstone 51 formed on the outer periphery of a disc-shaped grindstone support plate 52 and a rotary shaft 58 attached to the grindstone support plate 52 to rotate the grindstone 51. A grinding wheel rotating motor 53. On the outer peripheral portion of the grindstone 51, a concave groove 51a having a concave cross section that matches the convex shape of the cross section of the probe 23 is continuously formed on the entire circumference. As the grindstone 51, it is preferable to use a diamond grindstone or the like so that the probe 23 can be ground smoothly. However, the grindstone 51 is not limited to this, and for example, cubic boron nitride (CBN) such as borazon is used. Things can be used. Further, the grindstone 51 is covered with a cover 54 so that the grinding scraps generated from the tool 20 and the grindstone 51 are not scattered to the outside, and the tool insertion port 56 in which the tool 20 is disposed is disposed in the cover 54. Is provided on the upper surface, and a discharge port 57 for discharging grinding scraps and the like is provided on the lower surface.

  Referring to FIG. 3, when the probe 23 is ground for the regeneration of the tool 20, the worn tool 20 is moved to the upper side of the tool grinding device 5 while rotating, and the tip probe 23 is rotated. It grinds by making it contact with the ditch | groove 51a of the grindstone 51 which exists. At this time, referring to FIG. 5, the tool 20 is disposed on the base 7 so that the direction in which the joining line L of the workpieces W1 and W2 extends and the rotation direction of the grindstone 51 coincide with each other. Therefore, the tool 20 can be easily regenerated because the grindstone 51 can be used to grind the tool 20 while maintaining the advance angle θ.

  During the regenerating operation, the peripheral speed of the grindstone 51 is set to about 5 to 80 m / sec in the case of CBN (regular boron nitride) or diamond grindstone, but is not limited thereto. Thus, when the grinding is performed by rotating the grindstone 51 while the tool 20 is rotated, the tool 20 can be smoothly ground without being broken. The rotation speed of the tool 20 at the time of reproduction is set to an optimum rotation speed for grinding in consideration of the type of the grindstone 51, the peripheral speed of the grindstone 51, and the like. For example, the rotation speed of the tool 20 is preferably set to about 2000 rpm, but is not limited thereto.

  When grinding the tool 20, cold air and / or mist may be supplied around the grindstone 51. Thereby, by supplying cold air and mist during tool grinding, the roughness of the grinding surface of the grindstone 51 can be reduced, and the tool 20 can be ground smoothly and efficiently.

  By the above regenerating operation, the probe 23 which has become apparently long because the shoulder surface 22 of the tool 20 is significantly worn due to the repetition of the processing operation of the friction stir welding, the probe shape is adjusted, and the probe length is adjusted. Can be regenerated to an appropriate length corresponding to the thickness of the workpiece. Therefore, even if the processing operation on the workpiece is repeated using the same tool 20, it is possible to suppress the generation of defects at the bonded portion of the workpiece and realize a good bonding state. Further, since only the probe 23 is ground, the tool 20 can be regenerated easily and quickly. Furthermore, by reusing the worn tool 20 by regeneration, the tool life can be extended, the frequency of tool replacement can be reduced, and the processing cost of the workpiece can be reduced.

  Furthermore, the friction stir welding apparatus 1 is provided with a torque detection unit 33 (see FIG. 1) that detects the rotational torque of the tool rotation motor 23 that rotates the tool 20. Even during grinding with the grindstone 51, the rotational torque of the tool 20 is detected. Further, the friction stir welding apparatus 1 is provided with a regeneration control means (not shown) for controlling the grinding process to stop when the rotational torque detected by the torque detector 33 during tool grinding reaches a predetermined set value. ing.

  The set value as the rotational torque at which the grinding process is stopped is more ground than the rotational torque when the probe 23 of the tool 20 is lengthened due to repeated friction stir welding and the probe surface is ground. As a result, the rotational torque when the probe 23 becomes the initial appropriate shape and length is reduced, so that the grinding process is stopped when the rotational torque decreases and maintains a constant value for a predetermined time. Thereby, it is possible to perform good tool reproduction without wasting time and without cutting too much. The torque detector 33 detects the rotational torque of the grinding wheel rotation motor 53, and the regeneration control means stops the grinding process when the rotational torque of the grinding wheel rotation motor 53 reaches a predetermined set value. You may control to do.

  In addition, this invention is not limited only to the said embodiment, A various change is possible in the scope of the present invention. For example, the tool grinding apparatus 5 may grind and regenerate the shoulder surface 22 and the probe 23 of the tool 20 with the grindstone 51. If the shoulder surface 22 becomes significantly uneven due to wear due to repeated machining operations, the contact state between the shoulder surface 22 and the workpiece may become unstable and may interfere with a good bonding state, but the shoulder surface worn by the tool grinding device 5 may be disturbed. The contact state between the shoulder surface 22 and the workpiece can be satisfactorily maintained by restoring and reproducing the 22 and the probe 23 to a smooth state.

Example 1
1. Correlation of tool wear Using a tool made of Ni-based dual-duplex intermetallic compound alloy, two work materials (thin plates) made of iron-based material are brought into contact with each other by the friction stir welding apparatus 1 shown in FIG. The machining operation for friction stir welding was performed several times, and the correlation of the tool wear with the machining distance was investigated.
The tool has the shape shown in FIG. 3 and has a shoulder diameter (shoulder surface diameter) of 12 mm, a central probe diameter (probe diameter) of 4 mm, and a probe length (protrusion height of the probe from the shoulder surface). 0.44 mm.
The material of the tool includes 75 wt% of Ni, 7 atom% of Al, 13 atom% of V, 13 atom% of V, and 100 wt% of the total composition including Ta of 5 atom%, and B contains 50 ppm by weight. In addition, it is a Ni-based double-duplex intermetallic compound alloy having a double-duplex structure composed of a proeutectoid L1 ₂ phase and a (L1 ₂ + D0 ₂₂ ) eutectoid structure.
The workpiece is made of SUS430 and is a flat thin plate having a plate thickness of 1.0 mm and a length and width of 300 mm × 300 mm.
In the friction stir welding apparatus 1 shown in FIG. 1, a plate-like material is used as the backing material. In Example 1, the backing material is made of silicon nitride (Si ₃ N ₄ ), and is 30 × 30 mm square and 100 mm long. Three square bars were used in the joining direction.
Friction stir welding conditions are as follows: the tool height is set to a position lowered by 0.4 mm after the end of the shoulder surface comes into contact with the surface of the thin plate, and the tool is rotated at a forward angle of 3 degrees and a tool rotation speed of 1500 rpm. The sheet was pressed onto the joining line of the thin sheets, and after the tool emitted orange light by frictional heat, it was moved 250 mm linearly at a tool feed speed of 900 mm / min, and friction stir welding was performed.

  When the above machining operations are performed a plurality of times, the relationship between the machining distance and the amount of decrease in the shoulder height of the tool (the length from the connection position with the flange of the tool body to the shoulder surface) is shown in the graph of FIG. As shown in Fig. 5, the shoulder height of the tool decreased in proportion to the machining distance. As a result, from the graph of FIG. 6, tool wear correlation data indicating that the tool wears by about 0.02 mm for every machining distance of 250 mm was obtained under the above conditions.

2. Friction stir welding by adjusting the tool height Next, the tool wear correlation data is set in the tool height adjusting means of the friction stir welding apparatus, and the friction stir welding apparatus is operated once under the same conditions as above. When the friction stir welding with a machining distance of 250 mm is repeated a plurality of times, the tool height is lowered and the width is set to be lowered by 0.02 mm for each second and subsequent machining operations. Then, under the same conditions as described above, the friction stir welding operation in which one processing distance was 250 mm was continuously performed 13 times. In addition, the photograph of the junction part is shown in FIG.7, FIG.8, FIG.9 about the thin plate joining goods of the first time (1st time) of processing operation, the middle (7th time), and the last time (13th time), respectively.

3. Tensile test Next, in order to examine the strength of the joined portion where the thin plates are butt-joined, for the first (first), intermediate (7th) and final (13th) thin plate joints of the processing operation, A test piece was cut out in a direction perpendicular to the bonding direction of the test piece, and a tensile test was performed according to JISZ 2241 “Tensile test method for metal material”. The test piece had a width of 25 mm and a parallel part length of 50 mm in accordance with the shape of the JISZ 2201 No. 5 test piece. The crosshead speed during measurement was 20 mm / min.

(Example 2)
1. Correlation of tool wear In Example 2, the tool was the same as that in Example 1 except that the shoulder diameter was 10 mm and the probe length was 0.33 mm, and the workpiece was the same as in Example 1. A thin plate was used, and the friction stir welding conditions were the same as in Example 1 except that the number of rotations of the tool was 1800 rpm.

  When the above machining operations are performed a plurality of times, the relationship between the machining distance and the amount of decrease in the shoulder height of the tool is as follows. As shown in the graph of FIG. 10, the tool shoulder height decreases in proportion to the machining distance. did. As a result, from the graph of FIG. 10, tool wear correlation data indicating that the tool wears by about 0.04 mm for every processing distance of 250 mm was obtained under the above conditions.

2. Friction stir welding by adjusting the tool height In Example 2, the friction stir welding apparatus is controlled except that the tool height is lowered and set to be lowered by 0.04 mm for each second and subsequent machining operations. The same setting as in Example 1 was performed. Then, under the same conditions as described above, the friction stir welding process was performed 14 times continuously, with one machining distance being 250 mm. In addition, the photograph of the junction part is shown in FIG.11, FIG.12, FIG.13 about the thin plate joining goods of the first time (1st time) of processing operation, the middle (7th time), and the last time (14th time), respectively.

3. Tensile Test In Example 2, as in Example 1, a tensile test was performed on the thin plate joined product at the first (first), middle (7th), and final (14th) machining operations.

  Table 1 shows the conditions of each of the above examples, and Table 2 shows the appearance state and tensile test results for each processing operation.

  From Table 2, in Examples 1 and 2, the construction state of the joint portion was good in all processing operations in appearance. From this, even if the processing operation of friction stir welding to a thin plate of SUS430 is repeated using a tool made of a Ni-based double-duplex intermetallic compound alloy, the bonding state is a good finished state over all processing operations. Obtained.

About the tensile strength, in Example 1, it exists in the range of 507-512 N / mm < ² >, and the thing of the 1st thing of the processing operation fractured | ruptured in the junction part, and the tensile strength was 508 N / mm < ² >, but this is changed. The 13th processing operation that had a tensile strength of 507 N / mm ² was broken by the base material. In Examples in 2 in the range of 468~508N / mm ^2, although itself the first machining operation was ruptured its 508n / mm ² at the junction, which lower tensile strength 498N / mm ² The 7th processing operation and the 14th processing operation with a tensile strength of 468 N / mm ² were both broken by the base material. From this, it was found that each example has a sufficient strength that is not inferior to that of the SUS430 base material.

  From the above, even if the processing operation of friction stir welding to the workpiece (SUS430 thin plate) is repeated using the same tool (made of Ni-based two-phase intermetallic compound alloy), the processing distance and tool for each processing operation By controlling the tool height to be set low with a reduction width based on the correlation with wear, it is possible to cope with tool wear and to suppress the occurrence of defects at the joint and to achieve good friction stirring We were able to join.

Example 3
Next, in order to regenerate the probe of the worn tool and confirm that good friction stir welding can be performed with the regenerated tool, Example 3 below was performed.
In Example 3, the tool is the same as that of Example 1 except that the shoulder diameter is 12 mm and the probe length is 0.35 mm, and the workpiece is a thin plate made of SUS430 having the same size as that of Example 1. Friction stir welding was performed in the same manner as in Example 1 under the friction stir welding conditions.

After performing the above-mentioned friction stir welding process 23 times, the tool was regenerated by grinding the probe from the tool grinding apparatus shown in FIG. The grinding wheel of the tool grinding device uses a diamond electrodeposition grinding wheel, and the conditions during regeneration are such that the grinding wheel rotation motor is controlled at a rotational speed at which the peripheral speed of the grinding wheel is 8.9 m / sec, and the tool rotation is 2000 rpm. The tool is ground by controlling the tool rotation motor so that the grinding torque of the grinding wheel rotation motor reaches 1.2 N · m. It was.
Thereafter, after this tool was regenerated, friction stir welding was performed again under the same conditions as described above.
FIG. 14 shows a photograph of the joint portion by the machining operation before the tool reproduction, and FIG. 15 shows a photograph of the joint portion by the machining operation after the tool reproduction.

Next, as for the thin-plate bonded product before and after the regeneration, a test piece was prepared and a tensile test was performed in the same manner as in Example 1.
Table 3 shows the conditions and results of Example 3 described above.

As shown in Table 3, the thin-plate bonded product with the tool before recycling showed an uneven appearance on the appearance (see FIG. 14), and the tensile strength was as low as 370 N / mm ² , and the fracture occurred at the joint. From this, it was found that the bonding state was not good. On the other hand, the thin-plate bonded product using the regenerated tool has a good appearance and construction (see FIG. 15), has a high tensile strength of 502 N / mm ² , and breaks at the base metal position. Therefore, it was found that the bonding state was good and sufficient strength was obtained.

  From the above, it was found that even if the joint quality of the work piece deteriorates due to tool wear, friction stir welding with good joint quality can be performed again using the regenerated tool by tool regeneration. . Therefore, tool wear can be dealt with by tool regeneration, so that even if the machining operation on the workpiece is repeated using the same tool, the occurrence of defects in the machined part is suppressed and a good machining state is achieved. Can be realized.

1 Friction stir welding equipment (friction stir processing equipment)
2 Processing mechanism 5 Tool regeneration mechanism (tool grinding machine)
20 Tool 22 Shoulder surface 23 Probe 51 Grinding wheel 88 Tool height adjusting means L Joining line W1, W2 Workpiece (workpiece)
θ Advance angle

Claims (7)

A tool for projecting a probe on the shoulder surface and friction stir processing a workpiece made of a metal material;
Rotational drive means for rotating the tool;
Elevating drive means for setting the tool height to move the tool up and down and press against the workpiece from above,
Transfer drive means for moving the tool relative to the processing direction of the workpiece;
The above tool height when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the first material to be processed as the reference tool height, and the second and subsequent times. In order to secure the necessary contact area between the shoulder surface of the tool and the workpiece, in response to the decrease in the shoulder height due to tool wear due to machining operations A friction stir processing apparatus, comprising: a tool height adjusting means for controlling the lifting drive means so as to be set lower than the reference tool height by a predetermined lowering width. In the friction stir processing apparatus according to claim 1,
The tool is a friction stir processing apparatus made of a Ni-based two-phase intermetallic compound alloy. In the friction stir processing apparatus according to claim 1 or 2,
The workpiece is a friction stir processing apparatus made of a ferrous material plate. In the friction stir processing apparatus according to any one of claims 1 to 3,
A friction stir processing apparatus provided with a tool regeneration mechanism for grinding the tool worn by friction stir processing with a grindstone. In the friction stir processing apparatus according to claim 4,
The tool regeneration mechanism is a friction stir processing apparatus configured to grind only the probe of the tool with a grindstone. A tool for projecting a probe on the shoulder surface and friction stir processing a workpiece made of a metal material;
Rotational drive means for rotating the tool;
Elevating drive means for setting the tool height to move the tool up and down and press against the workpiece from above,
Transfer drive means for moving the tool relative to the processing direction of the workpiece;
The above tool height when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the first material to be processed as the reference tool height, and the second and subsequent times. For workpieces to be machined, only a predetermined reduction width is required to ensure the necessary contact area between the shoulder surface of the tool and the workpiece in response to tool wear due to machining operations. Tool height adjusting means for controlling the elevating drive means to be set lower than the reference tool height;
A tool regeneration mechanism for grinding the tool worn by friction stir processing with a grindstone;
At the time of reproduction by the tool reproduction mechanism, the tool is rotated so as to grind the tool while rotating the tool, and the output value of the torque detection means for detecting the rotation torque of the tool or the rotation torque of the grindstone is a predetermined value. friction stir processing apparatus comprising a reaches the set value and the reproduction control means for controlling to stop playing. A friction stir processing method for softening and processing a workpiece by friction heat generated by pressing a tool against a workpiece of metal material while rotating the tool,
The tool height for pressing the workpiece from the top when the same material is friction stir processed multiple times sequentially with the same tool is the tool height set for the workpiece to be processed first. For the workpiece to be processed at the second and subsequent times, the required contact between the shoulder surface of the tool and the workpiece corresponding to the amount of reduction in the shoulder height due to wear of the tool by the machining operation A friction stir processing method for processing a workpiece with a predetermined lowering width set lower than the reference tool height in order to secure an area.